[linux-audio-dev] Sound processing objects architecture, is it possible?

Steve Harris steve at plugin.org.uk
Wed Jan 24 17:55:36 UTC 2007

On 24 Jan 2007, at 15:52, Stefano D'Angelo wrote:

> 2007/1/24, Jay Vaughan <jayv at synth.net>:
>> At 20:08 +0100 22/1/07, Stefano D'Angelo wrote:
>> >What I'd like to work on is a sound processing architecture (LADSPA,
>> >VST, DSSI, etc.) wrapper, which hides the details of a particular
>> >implementation to audio program developers.
>> Nice idea.  Already done:
>> http://teragon.org/products/PluginCore/
>> >What do you think about it?
>> Would be nice if there were a GPL effort in the same way ..
>> --
>> ;
>> Jay Vaughan
> Well, it seems like LV2 can do (at least theorically) all of these
> already, altough some things might be a bit tricky (read the rest of
> the conversation).
> Now I'm seeking whether this approach (LV2 bridges plugins) can
> present practical problems and, in such case, I think it's better to
> solve them in LV2 than restart from scratch.
> To be true, there are two things I'm concerned about: one (less
> relevant, maybe) is RDF files... a bridge plugin should generate them
> for all installed plugins when it is loaded, and so it has to contain
> (or link to) code that can handle such syntax (I really don't
> understand why LV2 developers choose such language instead of XML,
> which is much more known and supported).

For one thing XML has no guarantee of extensibility, making it  

> The other one is more serious (but should have been also faced by
> vstserver, fst and dssi-vst): I'm talking about logical compatibility
> beetween LV2 and other standards (VST in this case) in handling some
> tasks (settings and session storing, banks/effects/programs metaphor,
> etc.). Does anyone know about these matters?

That was outside the remit, LV2 1.0 was just intended to replace  
LADSPA, and LADSPA doesn't have those features. However, LV2 is  
designed to be easy to extend to include such things.

> Then I think that it would be nice if some GUI programs could take
> advantage of trapping Xlib (or whatever) functions (LD_PRELOAD?) in
> order to embed plugin GUIs inside the app and/or have a library that
> autogenerates GUIs for non GUI-plugins (well... the XML GUI
> specification for LADSPA has been dropped in LV2 in favour of
> extensions?).
> ... it's such a complex matter :-P

The tripping point is the X event loop. Allegedly GTK and Qt have  
compatible event loops, but that's still quite limiting, and I don't  
think anyone's built a proof of concept.

- Steve

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